Wednesday, May 6, 2009

Recap of Wednesday AM storms (5/6/09)

Storm aftermath
The image above from MWN StormView Radar was snapped during the height of the storms overnight last night (early Wednesday, 3:14am).  The northern end of a line of storms associated with a mesoscale convective complex (MCS) grazed southern Shelby County between 2:30-3:30am.  About 30-40 miles south of the MS-TN line, the NWS was issuing Tornado Warnings for this supercell.  The image shows that StormView Radar picked up on a TVS (Tornado Vortex Signature - inverted magneta triangle above) associated with the tornado warning (box in magenta).  Severe Thunderstorm Warnings were also in effect (red boxes), as well as Flash Flood Warnings (green boxes).  The leading edge of the MCS extended from southern Shelby County westward through central AR at this time and the area was under a Severe Thunderstorm Watch and Flash Flood Watch.  Definitely a busy night for the NWS!  Locations across Shelby County reported 1.50-2.00" of rain overnight according to CoCoRaHS observers and NWS climate stations.

Storm Surveys
The TVS was tracked all the way from west of Tunica in east-central AR to north-central MS. According to Local Storm Reports, NWS storm surveys were done earlier today and indicate that the parent storm produced EF-1 tornado damage in Marvell, AR (Phillips County, across the river from Tunica) with trees and power lines down and damage to a retail establishment at about 2am.  Wind was estimated at 95-100 mph and the tornado had a path length of 100 yards and was 25 yards wide.

Further downstream, the storms spawned another brief twister of EF-1 intensity near Clarksdale, MS (Marshall County) at about 3:30am.  The tornado had similar characteristics (105 mph, 25 yards wide, 100 yard path length) to the Phillips County tornado and produced roof damage to some homes and snapped trees.  In addition to the tornado damage, trees and powerlines were downed all across north Mississippi due to the saturated ground and high wind.

What's in store?
So, is more of this violent weather in the offing?  Unfortunately, possibly.  I do believe most areas will get a reprieve through Thursday evening, though the Storm Prediction Center has the area highlighted in a SLIGHT RISK for Thursday.  I am forecasting storms to be few and far-between, though with plenty of moisture and temps soaring into the 80s with some sunshine, any storm that gets going could be strong Thursday afternoon. 

A frontal system that has been lingering around the area will make another push towards the metro Friday into the weekend (we are in a SLIGHT RISK again on Friday).  With upper-level impulses expected to move along that front, and with daytime heating creating instability in the afternoons, I expect thunderstorm chances to increase each day Friday into Sunday.  Another one of these MCS's can not be ruled out either.  If the formation and track of one of them is more certain, and it looks like the Mid-South is in the bulls-eye, obviously thunderstorm chances would increase a great deal.  All in all, I think most of us will get more rain before the end of the weekend.  Stay with and the MWN forecast for the latest on this dynamic scenario.

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